Key ConceptsLiquids have characteristic properties based upon the molecule they room made of.The properties of liquids depend on the attractions the molecules of the liquid have actually for each other and for other substances.Liquids deserve to dissolve certain other liquids, relying on the attractions between the molecule of both liquids. Polar liquids, favor water, dissolve various other liquids which space polar or rather polar.Polar liquids, favor water, perform not dissolve nonpolar liquids choose oil.
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Students will location isopropyl alcohol, mineral oil, and also corn syrup in water to view if any of these liquids dissolve in water. College student will extend their expertise and meaning of “dissolving” and see that certain, yet not all, liquids deserve to dissolve in water.
Students will certainly identify and control variables to help design a solubility test for different liquids in water. College student will have the ability to explain, ~ above the molecular level, why particular liquids, however not all, will certainly dissolve in water. Castle will additionally be maybe to explain that the solubility of a fluid is a characteristic residential property of that liquid.
Download the student activity sheet, and distribute one per student once specified in the activity. The activity sheet will certainly serve together the “Evaluate” component of every 5-E class plan.
Be certain you and the student wear effectively fitting goggles. Isopropil alcohol is flammable. Keep it away from flames or spark sources. Read and follow every warnings ~ above the label. Isopropil alcohol and also mineral oil need to be disposed of follow to regional regulations.
Materials for the DemonstrationsClear plastic cupWaterFood color Straw or popsicle stickIsopropyl alcohol (70% or higher)2 the same 100-mL i graduated cylinders
Materials for Each GroupWaterMineral oil isopropil alcohol (70% or higher)Corn syrup3 clean plastic cups5 small cupsPermanent marker or masking tape and also a pen for labeling cups3 straws or popsicle pole (for stirring)Laminated index card or card extended with wax paper Blue water Yellow isopropyl alcohol (70% or higher) 2 droppersToothpick or popsicle stick
Do a show to present the idea the solids aren’t the only substances that have the right to dissolve-liquids can likewise dissolve in liquids.
Ask students to do a prediction:Solids, prefer salt or sugar, have the right to dissolve in water. Perform you think the liquids can dissolve in water?
Question come Investigate
Does liquid food color dissolve in water?
Materials for the DemonstrationClear plastic cupWaterFood coloringStraw or popsicle stick
Note: A similar demonstration was conducted earlier in chapter 1 as evidence that molecules are in motion. Here, the demonstrate is provided to present the attraction in between water molecules and also the liquid coloring molecules that permits the color to dissolve in the water.
ProcedureHold increase a clean plastic cup or other clear container the room-temperature water. Include 1 or 2 fall of food coloring and enable the coloring come drift and spread in the water a bit.Explore
Have students command an activity to see how well isopropyl alcohol, mineral oil, and corn syrup dissolve in water.
Question come Investigate
Do isopropyl alcohol, mineral oil, and corn syrup dissolve in water?
Teacher ready for every GroupLabel 3 little cups Alcohol, Oil, and also Syrup for each group. Pour about 1 tablespoon of isopropil alcohol, mineral oil, and corn syrup right into their labeling cups.
Materials for Each GroupWaterIsopropyl alcohol (70% or higher) in tiny labeled cupMineral oil in tiny labeled cupCorn syrup in small labeled cup3 clean plastic cupsPermanent mite or masking tape and a pen for labeling cups3 straws or popsicle sticks because that stirring
ProcedureLabel 3 clean plastic cups Alcohol, Oil, and also Syrup.Pour water into all 3 labeled cups until each is about half-full. When looking at the water indigenous the side, gradually pour the alcohol into its labeled cup.Without stirring, clock to check out if the alcohol dissolves in the water on its own. Record your observations in the chart.After waiting around 10 seconds, row to check out if the alcohol dissolves. Record your observations. Repeat procedures 2–5 for oil and also corn syrup.
Expected ResultsThe alcohol looks type of gray and also swirly together it goes right into the water. The alcohol often tends to continue to be on the surface of the water due to the fact that it is less thick than water. It does not seem come dissolve automatically but dissolves once stirred. The oil stays on the surface ar of the water because it is less dense than water however it does not show up to mix lot at all with the water. Once stirred, the oil breaks apart a bit and also then develops a class again ~ above the surface of the water. The oil does no dissolve. The corn syrup sink in the water because it is an ext dense than water. It appears to stay there without lot initial dissolving. After stirring, the corn syrup dissolves into the water and the systems turns clear.
Discuss student observations.
Have students explain what the alcohol, oil, and corn syrup looked choose in the water and whether or no they dissolved.
Ask students:Can a fluid dissolve an additional liquid? Students have to realize that some liquids, but not all, can dissolve in water. Based upon your monitorings of the means isopropyl alcohol, mineral oil, and corn syrup dissolve in water, would certainly you say the solubility is a characteristic residential property of a liquid? Why?Yes. Solubility is a characteristics property since each liquid communicated with the water differently.Extend
Look much more closely in ~ the method water and alcohol mix.
Water and also alcohol do some pretty amazing things as soon as they mix. Tell students that you fancy water blue and isopropyl alcohol yellow so that they have the right to see the mixing better.
Question come Investigate
What happens as drops of water and also alcohol combine?
Teacher preparationEither laminate one index map for each group or covering an table of contents card through a piece of wax record and for sure the wax record with tape.Place about cup water in 1 cupAdd 2 drops of blue food coloring to the water. Location ¼ cup isopropil alcohol in another cup. Add 2 fall of yellow shade food coloring come the alcohol.Label 2 small cups water and alcohol because that each group. You may reuse the small cup labeling alcohol native the task in this lesson. Place around 1 teaspoon of every colored liquid into its pair of labeled cups for every group.
Materials because that Each GroupWater (colored blue)Isopropyl alcohol (70% or greater and fancy yellow)Laminated index card or card spanned with wax paper2 droppersToothpick or popsicle stick
ProcedureUse a dropper to place around 5 autumn of blue water together to do 1 big drop on your index card.Use another dropper to make a similar huge drop the yellow alcohol near to, however not touching, the blue drop.
Use a toothpick to traction the blue water towards the yellow alcohol till they touch. As shortly as the drops touch, background the toothpick away and do no stir.
The alcohol and water will type of “shake” or “jiggle” right at the area wherein they are mixing.
Discuss student observations.
Ask students:What do you observe when the fall of alcohol and also drop of water combine? college student will notice that the alcohol and also water seem to shake in ~ the area wherein they room mixing. Together the liquids mix, the yellow and blue colors incorporate to do green.
Tell students the the mix of alcohol and water is not totally understood on the molecule level. One reason for the shaky appearance can be that alcohol is less thick than water so as it mixes through water, the thickness of the all at once liquid changes. Alcohol (which alone floats top top water) sinks together it mixes. Probably lots of little “sinkings” make the mix look shaky. It could be that the an altering density causes light come refract in different ways to cause the shaky look. Possibly the alcohol interferes v water’s surface tension and causes a shaky look on the surface. The is additionally true that once water and alcohol room mixed, the equipment gets warmer. Probably the heat increases molecular activity at the surface, which in which method contributes to the shaky look.
Do a demonstrate to display that when water and also alcohol combine, the volume that the resulting solution is less than expected.
Tell students that the characteristic method water and also alcohol communicate with each various other causes another interesting phenomenon.
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Materials for the DemonstrationIsopropyl alcohol (90% or higher)Water2 the same 100-mL graduated cylinders
ProcedureMeasure 50 mL of isopropil alcohol and also pour it into a 100-mL graduated cylinder.
Measure 50 mL the water and include it come the alcohol in the 100-mL graduated cylinder.
The complete volume the the liquid will be about 97 or 98 mL. This is surprising since 50 mL the water + 50 mL the water amounts to 100 mL.
Explain come students that once the water and alcohol molecule interact, they rearrange and also actually take it up less room than if you include up your individual volumes.
Note: you may have heard the explanation the the water molecules space in the spaces between the alcohol molecules or the alcohol molecules room in the spaces in between the water molecules. This is also passive an explanation. It’s not favor marbles fall in the spaces in between golf balls. There is an energetic rearranging of molecule that space attracted to one another that outcomes in the final volume. In fact, adding any two liquids that have the right to dissolve in one one more will result in a volume that’s various from the sum of the separate liquid volumes. Alcohol and also water are regularly used as an example of this phenomenon because they are basic to get and show a particularly huge difference.